Pond Boss Forums INTRO Questions & Observations OH NO!

Heavy rains last night raised the water level in my pond 3.5'. First picture shows the flooded dock. Second picture confirms my worst fear. The buoyancy of the deck is pulling my telephone pole pilings from their seats, 18" on the one side and a few inches on the others. I'm sickened by this and have no idea how to fix this after the water recedes. Poles were originally approx. 5' into the clay, installed before the water. Please help if anyone has any suggestions.

This new photo upload has me perplexed. I read the instructions but it says that the file size exceeds the 2 MB limit!? It is just two photos from my cell phone. What am I doing wrong? This just isn't my day.

Wow, Blaine, sorry to hear about this. I just looked at the pic you posted under the photos section, but without being familiar with your dock, it's hard for me to see what you're obviously seeing.

I know you probably had a reason for building a dock that was anchored down by posts like that, but could you consider renovating your current structure into a floating setup once you are able to gain access again? It may allow you to salvage a lot of the structure that's there now, and eliminate the legs which created the susceptibility to this problem.

Again, really sorry to see you going through this. Best wishes, my friend.

[IMG]http://i153.photobucket.com/albums/s222/hesh44/photo-1.jpg

[IMG]http://i153.photobucket.com/albums/s222/hesh44/photo-2.jpg

This is the best I can do. Also below is the original condition of the dock.

[IMG]http://i153.photobucket.com/albums/s222/hesh44/DOCK1.jpg

I tapered my holes out at the bottom with a hand post-hole digger and added a half bag of dry readi-mix concrete around each poles before filling up the rest with dirt. They have held sturdy so far (about 5 years). We have had 5 inches of rain in the last 2 weeks (over half of that last night and this morning, and more is on the way! Where are you in central Indiana? I am about 30 miles west of Indy.

Wow - I have not had that bad of flooding, but we have a large emergency spillway.

Hi RAH. These poles are 12" in diameter. This is the worst flooding that I've seen since the pond was built in 2006. I live in the most extreme NE corner of Hamilton County, about 25 miles from 465 North on 37.

Any ideas on getting those poles pile driven back in to their holes? I originally augered 5' holes and placed the poles in. I'm at a loss.

assuming the holes surrounding the poles are likely firm clay soil, they should maintain their integrity and allow "pushing" the poles back down into the clay socket they popped out of. When the water recedes, a backhoe (or trackhoe) bucket might shove 'em right back home, nudging each one a little at a time.

Brettski,

Don't you think that the upward force would create a suction causing a wall collapse in the void? The most affected piling is 30' from shore. Will a boom arm from a backhoe reach that far?

Does a portable pile driver that can be assembled on top of the pole exist?

Not what you want to hear, but draining the pond down so you can work on the holes is probably the most reasonable way to keep this from happening again (maybe in ten years when it lets loose again), so you can add concrete around them). Alternaitvely, salvaging what you can and making this a floating dock might work (as suggested above). If the dock can be reset without draining the pond, you might want to consider if the posts could be weighted with concrete, rocks or metal, so this won't happen again. Chaining the posts to heavy chunks of conrete located under the dock (so divers won't clunk their heads) might be an inexpensive solution. You may get lucky and it will settle back into place (or close enough). This is a real bummer, but a lot of folks have swimming pools in their baseements, so it could be a lot worse.

P.S. My co-worker just headed home to Cicero to try and get his mowers out of a submerged shed. The rider will be difficult. The two subpumps in his house (under construction) could not keep up so the basement is flooded and the contractor will need to tear out at least 2 foot of drywall and let the insulation dry out. He could not get back with a 3rd pump in time. You guys really got hammered and more is on the way real soon. We are lucky that so far we are OK. Keep safe and let the water settle before getting in there!

My usual experience in conundrums like this is to completely over-react, prepare bringing in the National Guard, and keep Haliburton on hold on the 2nd line. Then, when things calm down, the 12 year old kid from next door says "why don't ya try pushin' 'em back down". I tell him to "shut up and scram, can't ya see we got brain surgeons workin' here". Then, after all the drilling and pile driving rigs are set up and the crew is about ready to start, one of the double overtime union guys has to stand up on top of one of the poles to get up high enough to hook a cable onto the 80 foot crane....and his weight pushes the pole back down to where it started.

That dock is quite wide and a lot of surface area putting pressure on them posts. I know hind site is 20x20 but those post should have had more like 3 bags of concrete put in them not a half a bag. I agree with RAH you may end of having to drain your pond to fix them the right way. Sorry to here of your trouble. I had something simular happen last year to me except my dock floats and I did not make my posts high enough and my dock came right off my post and floated across the pond up into the woods!! So I had to put longer posts in for them to slide up and down on. Of course my problem was not near as bad as yours is. Hope you can get it fixed bud.

Unfortunately there is no concrete. I didn't anticipate this scenario. I didn't figure a few inches of concrete around 12" diameter poles would make any difference. Didn't know that you could bevel out the base of a 5' hole. I don't think that I can bring myself to drain it. I would probably have to drain it completely. Pond is 13' at it's deepest, the poles are in 10' of water and 5' into the clay. I think I'll go out and bang my head against it until they are reseated.

LOL

Hey Blaine that is a problem. I would try and reseat them to then! Then like the above mentioned tie some serious weight to the end of your dock some how with some rope and eyebolts. It may cost a little but I think you can buy some pretty darn big anchors or something like that. Good luck bud!

Mine are not in that deep of water and not buried that deep, but the holes are flaired and the concrete fills the flair. I got the idea when I could not pull some very old cedar corner posts on a fence line using a tractor (in every way possible). When I dug them up, they had short cross pieces notched into the bottom. Using the natural strength of the soil really works. However in 10 feet of water, a floating dock might be longer lasting. I'll post some pictures of my combination fixed and floating dock when my son figures out how to load up the picturs(and he will).

Blaine,

I hate to see your predicament. How is your spillway holding up with that much water? There are a couple of companies that build piers and docks around my area in Alabama. They use pile drivers mounted on boats. It only takes @ 100 lbs. weight to due some serious pole driving in wet ground. There rigs aren't very complicated. Just a winch, pulleys, cable and a guide post. I have also used a large industrial (rental) are compressor to jet out the soil under poles to set them.

-JB

Thanks RC,RAH and HH.

RAH, How did you get the flare at the bottom of the hole unless it was really shallow? I wish I would have learned how to do that 4 years ago.

RC, Yea maybe hang 8-10 concrete building blocks on the pole for weight and pound the top with the biggest sledge hammer I can find until I collapse. I like it!
Unless of course I can find one of those floating pile drivers that HH is talking about.

I just angled the hand posthole digger and worked around the holes. They may have only been 42" deep. I was younger then.

OK









Both fixed and floating dock are 12' x 12'. Gang plank is 4' x 6'. Diagnal chains running under the gang plank are used for stabilizing the floating dock (each chain has a turnbuckle). The railing was added after a couple mishaps. We embrace a natural shoreline.

Blaine, even a backhoe with an extend-a-hoe wouldn't reach out that far. You are looking at an excavator for that type of reach. I'm at a loss unless you can get a portable pile driver.

Maybe rig up a tripod and find one of those old weights that they used to drive shallow wells??

Nice dock RAH. I like the toy hammock. I wish mine was as level as yours. It's unbelievable the engineering ideas I have come up with today that could have prevented my current situation.

Another possible idea would be to pull the bolts and lower the deck if it doesn't sink back into place. Kind of cheating but if all else fails...

Lowering the deck on the pole would work, but adding some weight fastened to the post, might be a good idea.

The uplift force due to bouyancy probably wasn't as much as you may think. Looking at your picture, I'd guess those 12 inch posts are only sticking out of the water maybe 4 ft or so at the normal pond level. Im going to guess your dock is about 20 ft long and varies from about 6 ft wide at the bank and bells out to 10 ft wide at the end of the dock. The space between the decking prevented any bouyancy from air pockets, so the wood bouyancy was the only source of uplift forces. Lets just say that the joists and decking give you an equivalent solid wooden cross section of 4 inches. That gives you roughly 20 cubic feet of wood for the portion of the dock between the first and second set of piers and roughly 27 cubic feet of wood between the second and third set of piers. Add roughly 20 cubic feet for the 24 total feet of piers sticking up out of the water (I am negelecting the submerged portion of the piers since they are waterlogged and probably are heavy enough to be "antibouyant" below the normal water level) and you have a total of about 71 cubic feet of wood contributing to the bouyancy force. Lets just round that to an even 75 cubic feet which is in all probability a huge overestimation. The density of water is about 62 pcf. Lets say that the bulk density of the wood on your dock is only half of that, 31 pcf, (most wood, especially treated wood is denser than this) and that leaves us with a total estimated uplift force of 75 cf X (62-31) pcf = 2325 lbs. Lets call it an even 2500 lb or 1.25 tons. And this force was distribed among the 6 piers, probably a bit unevenly, but nonetheless, spread to some degree among all of them.

As long as the clay "sockets" did not collapse, which I don't think they would since the uplift of the piers probably occured gradually as the water level rost and the voids beneath the piers filled with water as they were created, then you should be able to push them back into place.

As the water recedes, the bouyant force will go down and you won't have to fight back as hard to push the piers back into place. What if you built you a sturdy, but temporary framework out of 2X12's or 4X6's between the last the two displaced piers of your dock and line your frame work with empty 55 gallon drums? Then get yourself a pump and start filling the drums with water. Each full drum of water will give you about 380 lbs of force to push the piers back to their original place. 6 or 7 drums full should come close to overcoming the full bouyant force that caused you all the problems in the first place. As long as the clay sockets are intact, the piers should creep back into place. If that works, it shouldn't be too hard to devise a means of adding enough weight to resist the bouyant forces for the next time a flood event comes around.

If you try this, I would recommend fixing your framework to the piers with one very heavy duty bolt at each pier that goes all the way through the framework supports and the piers. Using only one bolt will allow the two piers to move differentially without putting your framework in as much of a bind and risking buckling or collapse. Keep in mind though, the bolts will ultimately have bear much of the load and need to be really really strong. You could try and build your framework to force most of the load to bear directly on top of the piers as much as possible, but you still will need some lateral support to counteract the overturning forces from the barrels full of water. You could also use concrete blocks, rocks, or other means of adding weight if you have that available. If not, barrels full of water provide pretty cheap weight.

Most importantly, if you decide to try this, I would suggest keeping your distance as much as possible when filling the barrels in case the framework collapses. Fixing the dock is definitely not worth somebody getting hurt over.

Key point is finding a way to get enough weight on the piers to push them back in place. Maybe somebody here can think of an easier, cheaper, or safer way to get 1000 or so pounds of weight on top of each of the displaced piers.....

The bolts don't have to be that big if they are the correct grade.

Given that in the above scenario you are trying to support 2500# between 6 posts. Lets say you have to support 2500# on each support for a fudge factor.

If that was the case, then a single 1/4" Grade 8 bolt on each support would be more than strong enough to hold 2500# on each support without failing.

Using a shear strength of 150,000 psi for a grade 8 bolt.
The following sq. in. figures are for the minor thread diameter for each given size. (UNC threads)

1/4" bolt has .0269 sq. in. shear is 4,035 pounds
3/8" bolt has .0678 sq. in. shear is 10,170 pounds
1/2" bolt has .1257 sq. in. shear is 18,855 pounds
3/4" bolt has .302 sq. in. shear is 45,300 pounds

Now if the pier is out of the water when you do this, treated wood weighs around 36.1# per cu. ft.

75 x 36.1 = 2707#
Add the weight of the filled barrels,55x8.35 = 460 say 500# for each filled barrel.
7 barrels x 500# each = 3500# 3500 + 2707 = 6207#

So, my wag is that a 3/8-16 x ? length Grade 8 bolt in each column would be strong enough to hold, even allowing for waterlogged wood. (cu. ft. of water is 62.43#) Now, would the wood stringers (joists) hold that weight without splitting? I dunno. If you can't find bolts that long, McMaster-Carr has grade 8 threaded rods.

Thanks for the bolt strength info.

For clarification, I think the framework would only need to be built between the two piers that are displaced so that the added weight will be concrentrated where it is needed the most.

From the figures you gave, the 3/8" bolts look to still be strong enough even if just two of them were used.